.center {
    background: white;
    text-align: center;
    width: 400px;
    margin-bottom: 100px;
}
.top{
    text-align: right;
    font-size: 20px;
}
/*顶部超链接样式*/
.top a{
    color: grey;
}
/*超链接悬浮样式*/
a:hover{
    color: red;
}
a{
    text-decoration: none;  /*去除下划线*/
}
.top img{
    float: left;
    margin-left: 100px;
}